Photoelectric transducer, image reading device, image forming apparatus, and image reading method

Abstract

A photoelectric transducer includes: a plurality of pixels arranged in one direction for each of colors of light to be received, and configured such that light is converted into an electrical signal in each of the plurality of pixels; a parallel processor configured to perform parallel processing on a plurality of electrical signals obtained through conversion in the pixels in synchronization with a spread-spectrum clock for each of pixel groups, each of the pixel groups including a predetermined number of pixels; and a corrector configured to correct an offset level of each of the plurality of electrical signals having undergone the parallel processing performed by the parallel processor, using one of values, each of the values being common within one of the pixel groups.

What is claimed is: 
     
       1. A photoelectric transducer comprising:
 a plurality of pixels arranged in one direction for each of colors of light to be received, and configured such that light is converted into an electrical signal in each of the plurality of pixels; 
 a parallel processor configured to simultaneously perform parallel processing including analog to digital conversion on a plurality of electrical signals obtained through conversion in the pixels in synchronization with a spread-spectrum clock for each of pixel groups, each of the pixel groups including a predetermined number of pixels; and 
 a corrector configured to correct an offset level of each of the plurality of electrical signals having undergone the parallel processing performed by the parallel processor, using one of values, each of the values being common within one of the pixel groups. 
 
     
     
       2. The photoelectric transducer according to  claim 1 , wherein each of the pixel groups includes a plurality of pixels configured to receive light of a same color. 
     
     
       3. The photoelectric transducer according to  claim 1 , further comprising
 a controller configured to control timing of the parallel processor performing parallel processing in synchronization with the spread-spectrum clock, wherein 
 the controller is configured to align a phase of a modulation period of the spread-spectrum clock for every period in which light is converted into electrical signals in the pixels. 
 
     
     
       4. The photoelectric transducer according to  claim 3 , wherein the controller is configured to perform control to reset the phase of the spread-spectrum clock each time light is converted into electrical signals in the pixels. 
     
     
       5. The photoelectric transducer according to  claim 4 , wherein the controller is configured to perform control to cause the period in which light is converted into electrical signals in the pixels, to be advanced or delayed by no more than twenty percent relative to any one of the modulation period and one-half of the modulation period. 
     
     
       6. The photoelectric transducer according to  claim 1 , wherein each of the pixel groups is for one of the colors of light to be received in the pixels. 
     
     
       7. The photoelectric transducer according to  claim 1 , wherein the parallel processor is configured to perform parallel processing on the plurality of electrical signals for each of the pixel groups at a point in time when a frequency of the spread-spectrum clock is equal to an approximate center frequency. 
     
     
       8. The photoelectric transducer according to  claim 1 , wherein the corrector is configured to correct the offset level using an output level of a light-shielded pixel provided for each of the pixel groups. 
     
     
       9. The photoelectric transducer according to  claim 8 , wherein the light-shielded pixel includes light-shielded pixels arranged at a plurality of different positions for each of the pixel groups. 
     
     
       10. The photoelectric transducer according to  claim 8 , wherein the corrector is configured to correct the offset level using an average value of output levels of the light-shielded pixel, the output levels being obtained during when light is converted in an electrical-signal in each of the pixels a plurality of times. 
     
     
       11. An image reading device comprising the photoelectric transducer according to  claim 1 . 
     
     
       12. An image forming apparatus comprising:
 the image reading device according to  claim 11 ; and 
 an image forming unit configured to form an image based on an output of the image reading device. 
 
     
     
       13. An image reading method comprising:
 simultaneously performing parallel processing including analog to digital conversion on a plurality of electrical signals in synchronization with a spread-spectrum clock, the electrical signals obtained through conversion in pixels, the pixels being arranged in one direction for each of colors of light to be received, and configured such that light is converted into an electrical signal in each of the plurality of pixels, each of pixel groups including a predetermined number of pixels; and 
 correcting an offset level of each of the plurality of electrical signals having undergone the parallel processing, using one of values, each of the values being common within one of the pixel groups. 
 
     
     
       14. A photoelectric transducer comprising:
 a plurality of pixels arranged in one direction for each of colors of light to be received, and configured such that light is converted into an electrical signal in each of the plurality of pixels; 
 a parallel processor configured to simultaneously perform parallel processing including analog to digital conversion on a plurality of electrical signals obtained through conversion in the pixels for each of pixel groups, each of the pixel groups including a predetermined number of pixels; and 
 a corrector configured to correct an offset level of each of the plurality of electrical signals having undergone the parallel processing performed by the parallel processor, using one of values, each of the values being common within one of the pixel groups, wherein 
 at least one processor of the photoelectric transducer other than the parallel processor operates in synchronization with a spread-spectrum clock.